It is customary to perform aircraft maintenance operations, particularly on commercial passenger aircraft, at predetermined, regular time intervals, whereby a multitude of maintenance checks must be performed. Such maintenance operations must be performed to assure the reliability and safety that is required for flight operations. Therefore, the components or component assemblies of individual aircraft types are regularly checked and/or replaced following a certain operating time duration. Due to the multitude and complexity of the aircraft components to be checked it is frequently time consuming and expensive to dismount the respective component then perform a fault check and testing of the functional capability of the particular component and then remount or reassemble the component or replace it by a new component or component assembly.
Another problem in connection with aircraft maintenance work is caused by possible faults that occur during flight but are not recognized during a check of the aircraft on the ground. Thus, the wear and tear of the actuators of the wing flap assemblies may, for example, be overlooked although such wear and tear in these flap actuators may be the cause that the entire aircraft begins to vibrate in response to control oscillations of the flap actuators. Such faults are hard to detect on the ground because these faults are normally not easily reproducible on the ground. It is difficult if not economically impossible to simulate actual flight conditions on the ground for maintenance purposes. Thus, a faulty flap actuator cannot conventionally be located with certainty. As a result, it is customary to replace even perfectly functional flap actuators for safety reasons. Such replacements involve substantial costs. Maintenance costs are a substantial proportion of the current costs of operating any commercial aircraft.